The distribution of strain along the soleus aponeurosis tendon was examined during voluntary contractions in vivo. Eight subjects performed cyclic isometric contractions (20 and 40% of maximal voluntary contraction). Displacement and strain in the apparent Achilles tendon and in the aponeurosis were calculated from cine phase-contrast magnetic resonance images acquired with a field of view of 32 cm. The apparent Achilles tendon lengthened 2.8 and 4.7% in 20 and 40% maximal voluntary contraction, respectively. The midregion of the aponeurosis, below the gastrocnemius insertion, lengthened 1.2 and 2.2%, but the distal aponeurosis shortened 2.1 and 2.5%, respectively. There was considerable variation in the three-dimensional anatomy of the aponeurosis and muscle-tendon junction. We suggest that the nonuniformity in aponeurosis strain within an individual was due to the presence of active and passive motor units along the length of the muscle, causing variable force along the measurement site. Force transmission along intrasoleus connective tissue may also be a significant source of nonuniform strain in the aponeurosis.

It is becoming increasingly apparent that precise knowledge of the anatomic features of muscle, aponeurosis, and tendons is necessary for understanding how a muscle-tendon complex generates force and accomplishes length changes. This report presents both anatomic and functional data from the human soleus muscle acquired by using magnetic resonance imaging. The results show a strong relationship between the complex three-dimensional structure of the muscle-tendon system and the intramuscular distribution of tissue velocities during in vivo isometric contractions. The proximal region of the muscle is unipennate, whereas the midregion has a radially bipennate hemicylindrical structure, and the distal region is quadripennate. Tissue velocity mapping shows that the highest velocity regions overlay the aponeuroses connected to the Achilles tendon. These are located on the anterior and posterior surfaces of the muscle. The lowest velocities overlay the aponeuroses connected to the origin of the muscle and are generally located intramuscularly.

The purpose of the present study was to examine effects of time-of-day-specific strength training on muscle hypertrophy and maximal strength in men. A training group underwent a 10-week preparatory training (wk 0-wk 10) scheduled between 17:00 and 19:00 hours. Thereafter, the subjects were randomized either to a morning or afternoon training group. They continued with a 10-week time-of-day-specific training (wk 11-wk 20) with training times between 07:00 and 09:00 hours and 17:00 and 19:00 hours in the morning group and afternoon groups, respectively. A control group did not train but was tested at all occasions. Quadriceps femoris (QF) cross-sectional areas (CSA) and volume were obtained by magnetic resonance imaging scan at week 10 and 20. Maximum voluntary isometric strength during unilateral knee extensions and half-squat 1 repetition maximum (1RM) were tested at week 0, 10, and 20 at a randomly given time of day between 09:00 and 16:00 hours. The QF average CSA and volume increased significantly (p < 0.001) in both the morning and afternoon training groups by 2.7% and 3.5%, respectively. The 0.8% difference between the training groups was not significant. The entire 20-week training period resulted in significant increases in maximum voluntary contraction and 1RM of similar magnitude in both training groups (p < 0.001 and p < 0.01, respectively) as compared with the control group. In conclusion, 10 weeks of strength training performed either in the morning or in the afternoon resulted in significant increases in QF muscle size. The magnitude of muscular hypertrophy did not statistically differ between the morning and afternoon training times. From a practical point of view, strength training in the morning and afternoon hours can be similarly efficient when aiming for muscle hypertrophy over a shorter period of time (<3 mo).

During dynamic activities it is difficult to assess in vivo length changes in human tendon and aponeurosis. The present study compared the outcome of two methods during unilateral squat jump and drop jump performances of four volunteers. Tendinous tissue elongation of vastus lateralis muscle was estimated using either (a) direct measurement of in vivo fascicle length change and muscletendon length estimation (kinematic method), or (b) prediction using a quadratic force function in combination with direct tendon force measurement (force method). In the kinematic method the most critical measures contributing to the 10% uncertainty were the fascicle angle and fraction of the estimated fascicle length. The force method was most sensitive to resting length, with 1% error margin. Both methods predicted the same pattern of tendinous elongation because of the monotonic force/length relationship. The magnitude of length change, however, differed considerably between both methods. Based on the force method, the changes were only 20% (absolute values) or 30% (strain values) of those obtained with the kinematic method. On average, the maximum strains were 5% with the force method and 15% with the kinematic method. This difference can be explained by the fact that the kinematic method characterizes not only the changes in tendon length but also includes aponeurosis strain along the muscle belly. In addition, the kinematic method may be affected by non-uniform distribution of fascicle length change along the length of the muscle. When applying either method for estimating the patterns of tendon and tendinous tissue length changes during human locomotion, the given methodological considerations should be acknowledged.

The study aims were to 1) examine profiles of perception of motor competence (PMC) in relation to actual motor competence (AMC), i.e. under-estimators (UEs), realistic estimators (REs) and over-estimators (OEs) and 2) investigate associations between the profiles and selected socioecological factors at the individual, family and environmental levels. PMC (Pictorial Scale of Perceived Movement Skill Competence) and AMC (Test of Gross Motor Development-Third Edition) were administered to a representative sample of children from 37 childcare centres in Finland (n=441;6.2±0.6yrs;52% boys). Socioecological factors were investigated using a parental questionnaire. The three profiles were formed based on age-and genderadjusted PMC and AMC z-scores. Multinomial logistic regression showed that OEs (n=81; p=0.04) tended to be younger than REs (n=306; p=0.04) and UEs (n=54; p=0.03). Parents of OEs reported more child health and developmental issues than parents of REs (p=0.03). Parents of UEs self-reported providing more support for physical activity than parents' of REs (p=0.04). REs tended to live in denser population areas than UEs (n=54; p=0.03). Whilst PMC profiles revealed some socioecological differences, future research needs to focus on a broader range of potential correlates and untangle methodological analyses challenges to deepen the knowledge about PMC development in children.